fs/xfs/xfs_buf.c:1534 xfs_buf_submit_bio() warn: unsigned '_x' is never less than zero.

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   0ad2507d5d93f39619fc42372c347d6006b64319
commit: fac69ec8cd743f509129deb5feae9e3f9ebc2cc8 xfs: simplify buffer I/O submission
date:   5 weeks ago
config: riscv-randconfig-r073-20250213 (https://download.01.org/0day-ci/archive/20250217/202502171326.j4Xd3I0j-lkp@intel.com/config)
compiler: riscv32-linux-gcc (GCC) 14.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202502171326.j4Xd3I0j-lkp@intel.com/

New smatch warnings:
fs/xfs/xfs_buf.c:1534 xfs_buf_submit_bio() warn: unsigned '_x' is never less than zero.

Old smatch warnings:
fs/xfs/xfs_linux.h:283 kmem_to_page() warn: unsigned '_x' is never less than zero.
fs/xfs/xfs_buf.c:761 xfs_buf_get_map() error: we previously assumed 'bp' could be null (see line 743)
arch/riscv/include/asm/atomic.h:218 arch_atomic_fetch_add_unless() warn: inconsistent indenting

vim +/_x +1534 fs/xfs/xfs_buf.c

  1518	
  1519	static void
  1520	xfs_buf_submit_bio(
  1521		struct xfs_buf		*bp)
  1522	{
  1523		unsigned int		size = BBTOB(bp->b_length);
  1524		unsigned int		map = 0, p;
  1525		struct blk_plug		plug;
  1526		struct bio		*bio;
  1527	
  1528		bio = bio_alloc(bp->b_target->bt_bdev, bp->b_page_count,
  1529				xfs_buf_bio_op(bp), GFP_NOIO);
  1530		bio->bi_private = bp;
  1531		bio->bi_end_io = xfs_buf_bio_end_io;
  1532	
  1533		if (bp->b_flags & _XBF_KMEM) {
> 1534			__bio_add_page(bio, virt_to_page(bp->b_addr), size,
  1535					bp->b_offset);
  1536		} else {
  1537			for (p = 0; p < bp->b_page_count; p++)
  1538				__bio_add_page(bio, bp->b_pages[p], PAGE_SIZE, 0);
  1539			bio->bi_iter.bi_size = size; /* limit to the actual size used */
  1540	
  1541			if (xfs_buf_is_vmapped(bp))
  1542				flush_kernel_vmap_range(bp->b_addr,
  1543						xfs_buf_vmap_len(bp));
  1544		}
  1545	
  1546		/*
  1547		 * If there is more than one map segment, split out a new bio for each
  1548		 * map except of the last one.  The last map is handled by the
  1549		 * remainder of the original bio outside the loop.
  1550		 */
  1551		blk_start_plug(&plug);
  1552		for (map = 0; map < bp->b_map_count - 1; map++) {
  1553			struct bio	*split;
  1554	
  1555			split = bio_split(bio, bp->b_maps[map].bm_len, GFP_NOFS,
  1556					&fs_bio_set);
  1557			split->bi_iter.bi_sector = bp->b_maps[map].bm_bn;
  1558			bio_chain(split, bio);
  1559			submit_bio(split);
  1560		}
  1561		bio->bi_iter.bi_sector = bp->b_maps[map].bm_bn;
  1562		submit_bio(bio);
  1563		blk_finish_plug(&plug);
  1564	}
  1565	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki